Signaling



(No Modell) C. E; SGRIBNER. SIGNALING APPLIANGE PoR TELEPHONE SWITGHBOARDS.

N0.575,1s1. 'Patented J&n.12,1897.

UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGN OR TO THE VESTERN ELECTRIC COMPANY, OF SAME PLACE.

SIGNALING APPLIANCE FOR TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 575,131, dated January 1,2, 1897. Application filed November 4, 1895. Renewed December 15, 1896. Serial No. 615,807. (No model.)

To all whom it may concern: wound upon the armature and serially cou- Beit known that I, CHARLES E. SCRIBNER, nected, the ground branch being applied at a citizen of the United States, residing at Chithe point of junction of the two coils. cago, in the county of Cook and State of Illi- The invention is illustrated inthe accom- 5 nois, have invented a certain new and usepanying drawings, in whichi'ul Improvement in Signaling Appliances for Figure l represents three stations A, B, and 'lelephone-Switchboards, (Case No. 408,) of C, connected bythree telephone-lines with the which the following is a full, clear, concise, switching apparatus of a telephone-switchand exact description, reference being had to board, which is provided with a signaling 6o ro the accompanying drawings, forming a part generator of the type which constitutes this of this specification. invention. v These telephone-lines exemplify My invention concerns the current-generthe three different conditions which must 'ator for operating the substation-bells of telbe met-namely, metallic circuits free from ephone-lines in an exchange system comprisgrounds, metallic circuits of which one line 15 ing both metallic and grounded circuit lines. conductor is accidentally grounded, and

Its purpose is to so apply the ground connecgrounded lines. Fig.. 2 illustrates, diagramtion ofthe generator for operating the bells matically, a construction of the armature of `on grounded lines that it may not interfere the signaling-generator.

with the trans-mission of signals on metallic- Referring to Fig. l, the substation is fur- 7o 2o circuit lines of which either conductor-is acnished with the usual receiving-telephone d,

cidentally grounded. transmitting-telephone d', signal-bell d2, gen- Itis customaryin telephone-exchange syserator d3, and telephone-switch df* for contems to employ a single generator of signalnecting the telephones and the signaling aping-current to operate the bells -on either pliances alternately with the line-circuit.

z 5 metallic or grounded circuits, or upon both The apparatus at station A isconnected by simultaneously. It is of course necessary to lines l and 2 with a spring-jack e in a teleprovide a ground connection, either permaphone-switchboard at the central station and nent or temporary, with the generator for with an annunciator f, the spring-jack being working over the grounded lines; but such a adapted to disconnect the annunciator from 8o 3o ground connection is undesirablein ringing the line when a plug is inserted into the jack. over metallic'circuits which are liable to ac- Station B is connected by line-wires 3 and 4 cidental ground contacts on either line conwith a similar spring-jack e and annunciator ductor, since the signaling-current from the f', and station C is included in a ground-cirgrounded generator may be short-circuited cuit 5, leading from earth at the substation 3 5 by an accidental ground which does not othto earth at the central station, and connected erwise seriously affect the operativeness of also with aspring-jack c2 and annunciator f2. the line. Lines l 2 may constitute a metallic circuit In my invention the ground connection is which is free from ground connections. Lines applied at the central point of the source of 3 4 are a similar metallic circuit, excepting 9o 4o signaling-current, as of the armature of the that an accidental ground has occurred upon generator. Then if the terminals of this genconductor Line 5 is obviously a -grounderator be applied to the line conductors of a circuit line. metallic circuit the entire source of current The operator at the central station is prowill be eective in operating the station-bell, vided with the usual connecting-plugs g and 45 While if one of the line conductors be groundringing-keyh, which, when depressed, coned, or if there be but one line conductor, as nect the terminals of the calling-generator i in the case of a grounded line, one-half of withthe contact-pieces oftheplug. Thisgenthe source ot' current will still be operative erator i may be constructed in the way illusto ring the station-bell. trated in Fig. 2 or in any equivalent manner. roo

5o In employing this invention in a magneto- As shown in Fig. 2, the armature consists generator ofy ordinary type two coils may be of a coil of Wire k, whose terminals are brought to contact-1iugs Z and Z', upon which bear suitable brushes m and fm. From the central point of this coil a branch G is led to a third contact-ring Z2, upon which a brush m2 rests. Of course the coil of wire Zt is supposed to be wound upon the usual core rotating between pole-pieces of magnets, as represented at 'L'. The rings Z and Zl maybe carried in any suit able manner upon the shaft of the generator, and an equivalent oi' the ring Z2 may be, if desired, the frame of the machine. The brush m2 or the frame of the machine is grounded by a conductor 7.

It in the device represented in Fig. 2 circuit be closed between brushes on and m', the whole coil 7s of the armature will of course be effective in ereatin g current in the closed circuit. If, however, circuit be closed between ground branch 7 and either brush m or m, one-half the armature will act to produce current in the circuit thus closed. Hence if plug g be inserted in spring-jaek e, the line of which is devoid of ground connections, the key ZL being depressed, a current will be set up impelled by the entire electromotive force of the armature. lf the plug be inserted in springjack e, one half the armature will be short-eireuitcd by the accidental ground on the line conductor 3, but the other half will have suiicient electromotive force to operate the bell d2 at the substation B. If the plug be inserted into spring-jack e2, similarly onehalf the armature will act to excite the bell at substation C. Thus this generator, provided with its permanent ground connection,

may be used indifferently upon grounded or metallic lines, and its action will not be interfered with by accidental grounds upon thc latter lines.

I claim as my inventionl. The combination with a plug-circuit of a telephone-swtehboard, a calling-key in the plug-circuit, and a source of signaling-current having its terminals connected with the switelrcontacts of the calling-key, of a ground connect-ion to the middle point of said source of current, substantially as described.

i?. The combination with a plug-circuit, a calling-key in the plug-circuit, and a generator of signaling-current having the terminals of its armature connected with switchcontacts of the calling-key, of a ground connection to the middle point of the active wire of said armature, as described.

The combination with a group of telephone-lines comprising both metallic and grounded circuit-lines provided with bells at their substations, a generator of signalingcurrent, and means for applying the terminals of said generator to the different lines, of a permanently-closed ground branch from the middle of the armature-Winding of said generator, substantially as described.

In witness whereof I hereunto subscribe my name this 24th day 0f September, A. D. 1895.

CHARLES E. SGRIBNER.

XVitnesses:

FRANK R. MCBERTY, ELLA EDLER. 

